Elevator dispatchers



Aug. 21, 1956 J. H. BORDEN 2,759,564

ELEVATOR DISPATCHERS Filed Oct. 29, 1953 4 Sheets-Sheet l jiquf IN VENTOR.

JOSEPH H BURDEN Aug. 21, 1956 J. H. BORDEN ELEVATOR DISPATCHERS FiledOct. 29, 1955 4 Sheds-Sheet 2 I .Ilg.

Aug. 21, 1956 J. H. BORDEN 5 ELEVATOR DISPATCHERS Filed 001.. 29, 1953 I4 Sheets-Sheet 5 -33 rMr-43, 45

JOSEPH H BURDEN El W United States Patent ELEVATOR DISPATCHERS Joseph H.Borden, Toledo, Ohio, assignor to Haughton Elevator Company, Toledo,Ohio, a corporation of Ohio Application October 29, 1953, Serial No.389,101

8 Claims. (Cl. 187-29) This invention relates to automatic passengerelevators and in particular to dispatching mechanism for automaticallykeeping the cars on a balanced dispatching schedule.

Dispatching machines for giving signals for the departure of elevatorcars from terminal floors are quite well known and widely used. Theusual dispatching machine controlling an even number of cars usuallygives signals simultaneously at the upper and lower terminal floors inorder that cars may be dispatched from these floors simultaneously. Aslong as an even number of cars are in service such an arrangement tendsto keep the cars uniformly spaced provided no unusual operatingconditions occur. The dispatching machines are also arranged so that ifan odd number of cars are in service the dispatching signals are givenalternately at the terminals so as to maintain a uniform spacing of thecars in their respective trips. It occasionally happens with suchdispatching machines that the system gets out of balance particularly ifa car having received a signal to depart does not depart prior to thenext signal. Thus for a given interval of time a certain number of carsmay have been dispatched from one terminal and a different number fromthe other terminal. This results in assigning more cars to one trip thanto the other, i. e. more cars may be conditioned for upward travel orwaiting up dispatch than are conditioned for down trip or awaiting downdispatch. Several rather complicated arrangements have been devised forcorrecting or rebalancing the system when such a condition occurs. Othersystems require the intervention of an attendant to rebalance thesystem.

The principal object of this invention is to provide a dispatchingsystem Which not only allows manual dispatching or starter controlleddispatching at a terminal floor but which also maintains a balanceddispatching condition even though cars may fail to depart on schedule ormay be unduly delayed during a trip.

Another object of the invention is to provide a dispatching system whichautomatically adjusts itself to ordinary variations in trafiic demand.

A still further object of the invention is to provide an automaticdispatching mechanism which may make corrections in dispatchingintervals as required to maintain balance without materially changingthe average dispatching time interval for the system.

A still further object of the invention is to provide a dispatchingmechanism that automatically adapts itself to an odd number of cars oran even number of cars without attention on the part of a starter orother attendant.

More specific objects and advantages are apparent from the followingdescription of a preferred form of the invention.

According to the invention a pair of motor driven timers, one for theupper terminal and one for the lower terminal, are employed withdispatching mechanism for I each terminal and other means responsive tothe number Patented Aug. 21,

of cars at a terminal are employed to speed up the dispatcher timermotor at that terminal having more than a predetermined number of carsstanding thereat and to simultaneously slow down the dispatcher timermotor for that terminal having a fewer number of cars awaiting dispatch.The amount of speeding up and slowing down of the dispatcher timingmotors may be adjusted so as to maintain a generally constant averagetime interval. In a dispatching mechanism constructed according to theinvention a set of sensitive relays one for each terminal are provided,the relays being operated as soon as a predetermined number of carsaccumulate at the terminal. If such a predetermined number of carsaccumulate at one terminal the dispatching machine for that particularterminal is speeded up to decrease the timing interval while thedispatching machine for the opposite terminal is slowed down a generallyequal amount. The resulting speed change balances the system to get asmany cars on the up travel and awaiting up dispatch as there are on thedown travel and awaiting down dispatch. This balancing takes place eventhough one or the other of the timers may be detented as when there areno cars available for dispatching, and also rebalances the system shouldone of the cars be dispatched ahead of time by manual dispatching fromone terminal or the other.

Means are also provided for adjusting, in the same direction, therespective speeds of the two timers and thus adjust the average timinginterval according to traffic requirements. It is ordinarily consideredgood practice to arrange the dispatching interval such that it is equalor approximately equal to the round trip time of an elevator car dividedby the number of cars in service. The average round trip time may betaken as the time required when there is a moderate to heavy amount oftraffic. When the traffic is light, particularly in one direction, thecars tend to run ahead of schedule and accumulate at the terminal floor.With the dispatching machine according to the invention thisaccumulation occurs until more than a certain number of cars collect atthe terminal. Then, during one or more dispatching intervals, one of thetimers runs faster than the other, preferably twice as fast, until thecars are again evenly distributed.

A preferred form of the invention is illustrated in the accompanyingdrawings.

In the drawings:

Figure I is a generally schematic illustration of a plurality ofelevators serving a plurality of floors.

Figure II is a simplified drawing of a dispatching machine suitable fortiming the dispatching intervals.

Figure III is a detail view of a slip clutch for the dispatching machinetimer.

Figures IV and V are timing diagrams illustrating the sequence ofoperation of the contacts that are periodically operated by the timingmotors.

Figure VI is a schematic wiring diagram showing the means responsive tothe departure of a car from a terminal floor for resetting thedispatching relays and for resetting the means signaling the number ofcars standing at a terminal.

Figure VII is a schematic wiring diagram of the means employed toascertain the number of cars awaiting dispatch at a terminal.

Figure VIII is a schematic wiring diagram showing the control circuitsfor the timing motors and the means for adjusting the speed of thetiming motors.

Figure IX is a schematic wiring diagram of the dispatching relay system.

An elevator system including the dispatching mechanism according to theinvention may comprise a bank of elevators having any practical numberof cars. Figure I illustrates such a bank having five cars, 1a, 1b, 1c,1d and 3 10 arranged to serve a plurality of floors. The cars aresimilar and each is suspended by a set of cables 2 passing over a drivesheave 3 and attached to a counterweight 4. The drive sheave 3 ismounted on a motor armature shaft 5 of an elevator drive motor 6. Theshaft 5 is also arranged to drive a floor selector machine 7.

Although not shown in the drawing, common hall buttons for all of theelevators are provided at each of the floors for registering calls forservice and corresponding control buttons in each of the cars areprovided for registering destination calls. According to common practicethe several selector machines 7 have certain of their contacts connectedin parallel so that a floor call is answered by the first car toapproach that floor in a direction corresponding to the call.

In order that the elevator cars may be kept in spaced relation in theirtravel up and down the shafts and thus provide the best service it isnecessary that they be given dispatch signals at one or both terminals.The dispatching signals are ordinarily given at more or less regularintervals of time and these intervals may be determined either by timingrelays or by motor driven timers. Ac cording to the invention variablespeed motor driven timers are employed for timing the intervals. Such amotor driven timer is schematically illustrated in Figure II. This timercomprises a variable speed timing motor TM having an armature shaft 8connected through reduction gearing 9 and output shaft 10 to a frictionclutch 11 driving a pinion 12. The pinion 12 meshes with and drives alarger gear 13 mounted on a cam shaft 14. A plurality of earns 15, 16and 17 of the cam shaft operate contacts TMB-A, TMB-B and TMB-C of thecontrol system. These contacts appear at lines 54, 52 and 50respectively, of Figure IX. A timer reset motor 18 is connected througha pinion 19 to the gear wheel 13.

The timing motor TM when driving through the gear reducer 9 drives thecam shaft 14 at a slow speed. When it is desired to reset the timer thereset motor 18 drives the gear at a much faster speed the difference inspeed being accommodated by slippage of the pinion 12 of the frictionclutch 11.

This friction clutch 11 is shown in greater detail in Figure III. Itcomprises a first washer or stop member 20 pinned to the output shaft 10and frictionally engaging one side of the pinion 12. A washer 21engaging the other side of the pinion 12 is held by a helicalcompression spring 22. The spring is compressed between the washer 21and a nut 23 threaded onto the end of the output shaft. By adjustment ofthe tension of the spring 22 the friction may be adjusted so as to drivefrom the output shaft 10 to the cam shaft 14 when the reset motor 18 isde-energized and yet to permit the reset motor 18 to slip the clutchwhen it is necessary or desirable to reset the timer.

The sequence or timing of the operation of the contacts TMBA, B and C ofthe bottom terminal timer is illustrated in Figure IV. As shown thereinas the cam shaft revolves from the initial starting position marked zerowhere the contacts A are momentarily closed, the contact operator 25first momentarily opens contacts C at about thirty degrees of rotationand then continues around for another three hundred degrees beforemomentarily closing contacts B. While only a single is operator is shownin this figure it is to be understood that each cam has a high point foroperating its associated contact and that those high points and theswitches are oriented to give the above described timing.

The contacts C are used in the control circuit in connection withresetting the timer. At the upper terminal if resetting is not employedthese contacts are omitted and only the contacts 'A and B and theassociated cams used. The timing for this arrangement is shown in FigureV.

The actual dispatching of the cars or the giving of the dispatch signalsis controlled by a pair of latch relays, one for the upper terminal andone for the lower terminal. The latch relays are reset when it isdesired to dispatch a car and give a dispatch signal. The relays aretripped or returned to their non-reset or unlatched position as the nextcar leaves the corresponding terminal.

Relays the operating coils of which are shown:

Relay Diagram Function Symbol Line EDT-2 23 Bottom terminal minimumstanding time.

Energized when no car is at bottom terminal.

DI) 43 Detent relay down dispatcher. Energized to interrupt downdispatching.

DU 52 Detent relay up dispatcher. Energized to interrupt up dispatching.

KD 4 Down dispatch relay trip coil. Operates when a car responds to downdispatch signal.

KD 45 Down dispatch reset coil operates from down dispatcher timer togive dispatch signal.

KU 9 Up dispatch relay trip coil. Operates when a car responds to updispatch signal.

KU 54 Up dispatch reset coil operates from up dispatcher timer to giveup dispatch signal.

KUT 12 Slow release timer relay for up dispatcher reset circuits.

MDT 48 Manual dispatch time relay. Slow release.

Resets up dispatcher to shorten interval.

NCB-Z 19 Car counting relaybottom terminal, operates when two or morecars are at terminal.

NCB- 21 Car counting relay bottom terminal, operates when three or morecars are at the terminal.

NCBR 7 Reset relay, bottom terminal. Resets car counting relays when acar leaves the terminal.

NOT-2 14 Upper terminal car counting relay, energized when two or morecars are at top terminal.

NOT-30-...-. 16 Upper terminal car counting relay, energized when threeor more cars are at top terminal.

NOIR 2 Upper terminal car counting relay reset.

energized as a car leaves top terminal.

RF l. 49 Dispatch interval reset relay. Energized to operate reset motor18.

SR 56 Starters release relay. Permits supervisor to hold car afterexpiration of dispatching time interval.

TMB 37 Dispatcher timing motor, bottom terminal.

TMI 33 Dispatcher timing motor. upper terminal.

Relays, the operating coils of which are not shown; that are individualto each car:

Symbol Function Bottom terminal relay. Indicates that the associated caris at the bottom terminal.

Down direction control relay.

In service relay.

Top terminal relay. Indicates that the associated car is at the topterminal.

Up direction control relay.

Bottom terminal minimum standing time relay.

Energized when no cars are at the terminal. I

Top terminal minimum standing time. Energized when no cars are at theterminal.

Up peak traflic program.

Heavy up trafiic program.

Night traffic program.

Dispatching interval program control.

Immediate down dispatch control.

Immediate up dispatch control.

Call controlled starting signal.

Special program. Two cars in service.

Figure VI illustrates the circuits for tripping the dispatch relays asthe car leaves the terminal. As shown in this figure brushes 30, one foreach car, are connected to direct current power lead L3 by way ofin-service relay contacts IS, one set of such contacts for eachelevator. These in-service relay contacts IS are closed as long as thecorresponding elevator car is in service with its motor generator setrunning and the car ready to answer calls. The brushes 30A and 30C, forelevators A and C respectively, are shown in relation to selectormachine con tacts 31A and 31C in the position that the brushes occupywhen the corresponding cars are standing at the upper terminal. Selectorbrushes 30B and 30E are shown in the positions they occupy with respectto bottom terminal contacts 32B and 32B when the cars are standing atthe lower terminal. The brush 30D for the fourth elevator is shownintermediate its contacts indicating that that car is on its tripbetween terminals. As a car starts down from the upper terminal whetherit be the car A or the car Q it completes a circuit from the line L3through its in-service relay contacts IS such as are illustrated inlines 1 or 3, then through its brush A or 30C to the correspondingselector machine terminal 31A or 31C, then through contacts DF of itsdown direction field relay to a lead 33 that is connected through a coilof a reset relay NCTR (line 2) to the return lead L4. At the same time aparallel circuit is completed through a lead 34 in line 4 and a tripcoil KB of a down-dispatch relay KD (line 4). Reset relay NCTR hascontacts in line 15 arranged to momentarily de-energize number relaysNCT2 and NCT3 which indicates the number of cars at the top terminal.This reset relay NCTR is provided because the pull-in and releasecurrents of sensitive relays are so widely different that it is notpractical to depend upon a small enough difference so that the relayoperates if one more than a prescribed number of cars is at the terminaland releases by itself as soon as one car leaves. However, by using thereset relay NCTR the car counting or number relays NCT2 or NCT3 ofFigure VII are momentarily released as each car leaves and thenre-energized if a sufiicient number of cars still remain at theterminal.

As the cars leave the bottom terminal corresponding circuits arecompleted from the supply lead L3 through the in-service relay contactsIS, the brushes 30, to the corresponding bottom contacts 32, thenthrough the up-field relay contacts UF that are closed only when a caris conditioned for upward travel, and then through the up dispatch relaytrip coil KU to the return lead L4. A bottom terminal reset relay NCBR,for resetting number relays NCBZ and NCB3 indicating the number of carsat the bottom terminals, is connected in parallel with the up dispatchtrip coil KU so as to be momentarily energized as the car leaves thebottom terminal.

FigureVII illustrates the circuits employed for determining the numberof cars standing at a terminal and available for dispatching. As long asthe car is in service its in-service relay contacts IS appearing at theleft in Figure VII are closed. Likewise when a car arrives at a terminaleither top or bottom the corresponding terminal relay is energized so asto close its contacts TT if it be an upper or top terminal relay orcontacts BT if it be a bottom terminal relay. There are a pair of suchterminal relays for each car. Each car standing at the top terminal withits motor generator set running (so that it is in service) operates itsterminal relay so that current may flow from the supply lead L3 throughthe corresponding in-service contacts IS, the top terminal relaycontacts TT for the corresponding car, then through correspondingresistors 35, 36, 37, 38 or 39. From the resistors the current dividesand flows through the coils of number relays NCT2 and NCT3 which areconnected in parallel and then through normally closed contacts NCTR ofthe reset relay NCTR. The resistors to 39 are selected according to thecurrent sensitivity of the relays so that one car alone at a terminalfloor is insufiicient to energize either relay. However, if two carsarrive at the top terminal simultaneously thus placing two of theresistors 35 to 39 in parallel enough current flows through the relaycoils to energize or operate the relay NCT2. If a third car arrives atthat floor before either of the other two leaves enough additionalcurrent is supplied by the third resistor connected in parallel so thatthe other number relay NCT3 is also energized. These number relays NCT2and NCT3, control various circuits of the dispatching mechanism tomaintain generally balanced operation of the system. The first of these,the relays NCT2 and NCB2 are only used during certain periods of the daywhen perhaps only two cars are operating and serve to dispatch a carfrom a terminal floor as soon as the other car arrives at that floor.The other number relay NCT3 is employed in connection with thedispatching mechanism during the time when all cars are operating andserves to speed up the dispatching machine at the top terminal and slowdown the machine at the bottom terminal whenever three or more cars arestanding at the top terminal. As was mentioned previously the normallyclosed contacts NCTR in line 15 are included to momentarily de-energizethe relays NCT2 and NCT3 whenever a car leaves the upper terminal. Thuswhether one or both of these relays are energized depends upon thenumber of cars remaining at the terminal. It is not necessary that theserelays be closely adjusted for drop-out current, i. e. the current flowwhich will just fail to sustain the relay in operated condition, sincethe relays are both de-energized and re-energized each time a carleaves. Therefore a relay is energized only if enough current is flowingto cause it to pull in.

Similar circuits using resistors 40 to 44 inclusive are employed toenergize bottom terminal number relays NCBZ and NCB3. The first of theseis energized as long as two or more cars are standing at the lowerterminal while the second of these relays is energized if three or morecars are at the terminal. Likewise these relays are momentarilyde-energized as a car in leaving the bottom terminal operates its resetrelay NCBR of Figure VI thereby momentarily breaking the circuit at thecontacts NCBR in line 20. Also included in Figure VII is an up dispatchtimer relay KUT shown in line 12. This relay takes part in the resettingof the up dispatch timer.

Another relay BDTZ shown at the bottom of Figure VII (line 23) is usedin controlling the resetting operation during periods of heavy uptraffic when there are no cars at the bottom terminal. This relay BDT2has contacts in line 49 of Figure IX which cooperate with other contactsin controlling the timer reset motor 18. As shown in Figure VII, up-peakprogram contacts H1 in line 23 are closed during periods of up-peakpassenger traflic while heavy-up program contacts H4 are closed when thetralfic is predominantly up. The other set of contacts in line 23, thecontacts BDT, are contacts of a bottom terminal control relay whichrelay is energized to close the contacts as long as there are no carswaiting at the lower floor or lower terminal in condition to receivepassengers.

The circuits for driving the timing motors for the top and bottomdispatching machines and for controlling the speed of these motorsaccording to demand are illustrated in Figure VIII. As shown in FigureVIII, power from alternating current supply leads L1 and L2 is fedthrough normally closed contacts H6 of a night program relay in line 25(to de-energize the system during the night) or contacts THA of a twocar special service relay THA. From these contacts, closed duringregular operation; the current may flow through lead 45' to anautotransformer AT shown in line 27. Also permanently connected to thelead 45 is a primary 46 of a motor current supply transformer 47. Thereturn side of the primary 46 is connected through down detent relaycontacts DD in line 3 1, and a lead 43, to a switch arm 49 adapted tocontact any of a plurality of switch points or taps 50 of theauto-transformer. Current may also flow from the lead 45 to a full waverectifier 51 shown at lines 38 and 39 and back through the return leadL2. The rectifier 51 has output leads L3 and L4 which supply current tothe circuits shown in Figures VI, VII and IX as well as to the shuntfields TMTF of the top terminal timer motor TMT and to the shunt fieldTMBF of the bottom terminal timing motor TMB. These fields are shown atline dill of Figure VIII.

The armature circuit of the top timing motor TMT at line 33 is energizedfrom. a secondary 52 of the trans former 47 by way of a full waverectifier 53 one terminal which is connected through a lead 54 to oneside of the armature TMT of the timing motor. From the rectifier 5'3current also flows through a second rectifier 55, and a third rectifier56 the output lea-d 57 of which is connected to the other side of thearmature of the timing motor. The second rectifier is energized from asecondary 58 of a second transformer 59 having a primary 60 connectedthrough contacts NCB3 in line 31) (of the bottom terminal number relayNCB3) to the lead 45. These particular contacts are closed as long asfewer than three cars are located at the bottom terminal. Should threeor more cars be simultaneously standing at the bottom terminal thecontacts NCB3 in line 34) are opened to deenergize the transformer 59and thus decrease the speed of the timing motor TMT. A third transformer61 having a primary 62 connected to the supply lead 45 through normallyopen contacts NCT3 in line 28 has its secondary 63 arranged to energizethe third rectifier 56 and thus supply additional voltage to the timingmotor TMT whenever the contacts NCT3 are closed, i. e. whenever three ormore cars are simultaneously standing at the upper terminal. Thus thetiming motor for the top dispatching machine, the timing motor TMT, runsat normal speed as long as there are less than three cars at eitherterminal. Should three cars be standing simultaneously at the topterminal the contacts NTC3 are closed which adds the voltage of thetransformer 61 to the supply circuit for the timer motor armature thusincreasing its speed. Likewise, if three or more cars accumulate at thebottom terminal the contacts NCB3 in line 35) are opened thus decreasingthe voltage supplied to the timer motor armature thereby decreasing itsspeed. Similar circuits including rectifiers 64, 65, 66 energized fromtransformers 67, 68 and 69 respectively supply current to the armaturecircuit of the bottom terminal timing motor TMB. The transformer 67 hasits primary 70 continuously energized from the lead 45 as long as the updetent contacts DU in line 37 remain closed. Thus the secondary 71 ofthe transformer 67 continuously supplies alternating current voltage tothe rectifier 64 to supply voltage to the timing motor armature circuit.Likewise as long as there are less than three cars at the upper terminalcontacts NCT3 in line 36 are closed to energize a primary 72 of thesecond transformer 63 so that its secondary 73 may supply voltage to therectifier 65 and thus increase the voltages applied to the armature ofthe timing motor. Likewise if more than three cars accumulate at thelower terminal the contacts NCB3 in line 35 are closed to energizeprimary 74 of the transformer 69 so that its secondary 75 suppliesvoltage to the rectifier 66 and thus further increases the voltagesupply to the timing motor TMB.

In this arrangement the accumulation of three or more cars at the upperterminal causes the upper dispatch timer motor to run faster and causesthe bottom dispatch motor to run slower thus tending to resynchronizethe timers and secure balance in the dispatching of the cars. If, in alarger bank of a elevators having six or more cars, three cars shouldsimultaneously arrive at the upper terminal while three cars are at thebottom terminal then both of the car counting relays NCT3 and NCB3 wouldbe energized thus energizing transformers 61and 69 and de-energizingtransformers 59 and 68 thus leaving the timing motors to run at normalspeed. Thus the difference in timing motor speeds occurs as long asthere is an unbalance in the number of cars at the terminals and thereare more than two cars, i. e. three or more cars, at one of theterminals.

It should be noted that the average dispatch interval is not changed bythe operation of the car counting relays since one of the dispatchingtiming motors is speeded up while the other is slowed up thusmaintaining a nearly constant average.

The average timing interval may be adjusted by selection of a proper tap50 of the autotransformer AT in line 27 as may be required to supply theproper voltage between the leads 45 and 48. If a clock operated programselector is employed and it is desirable to use different timingintervals for different parts of the program, the switch arm 49 may bebrought around to a terminal 76 so that the voltage may be selectedaccording to which one of the program selector contacts PS1 to PS5 inlines 29 to 33 may be closed, these contacts being connected throughmulticonductor cable 77 and branch leads 78 to the tenninals 50 of theautotransformer.

In this arrangement the timing motors tend to runat the same speedthereby giving approximately the same number of dispatching signals atthe upper terminal as are given at the bottom terminal. These signalsare not necessarily given simultaneously as they are in some dispatchingsystems nor are they given exactly half cycle apart as they are inmachines designed for dispatching.

an odd number of cars. Rather the signals are given at more or lessuniform time intervals and if the system, for any reason, gets out ofbalance such that more than a certain number of cars accumulate at oneterminal one of the timers is speeded up and the other slowed down untilthe excess number of cars are dispatched and the system rebalanced.Since this rebalancing takes place regardless of the cause of theunbalance this system is immediately effective in maintaining correctbalance as cars are taken in or out of service or if they are undulydelayed for any reason.

The remaining control circuits for the dispatching system areillustrated in Figure IX. In this figure the circuits shown in lines 41to 46 inclusive relate to dispatching from the upper terminal while theremainder of the circuits shown in this figure relate to dispatchingfrom the bottom terminal.

As was mentioned previously the down dispatch relay KD and the updispatch relay KU are latch relays which are arranged to be reset by therespective dispatch timing motor contacts TMT-A or TMB-A. When the upperterminal down dispatch KD is reset by the current flow from the line L3through the timing motor cam operated contacts TMT-A shown in line 45the dispatch relay KD is reset and gives a dispatch signal to theelevators at the upper floors until one of the elevators leaves thatterminal. The departing car trips the upper terminal dispatch relay KDby current fiow through the lead L3, lead 34 (line 4, Fig. VI) to thereturn lead L4. The upper dispatch timing motor is stopped or detentedshould the timer close its timing contacts B in line 43 at such time as(a) there are no signals registered, as indicated by starting signalrelay contacts SSC in line 44 being closed; (b) there is no car at theupper terminal available for dispatching, as indicated by closure ofcontacts CDT; or (c) timed dispatching is not required as indicated byclosure of the RD contacts in line 41. This last condition may occurduring periods of heavy up traffic when it is desired to send the carsdown as soon as they are available. A fourth set of contacts TH-l inline 42 relate to a two car operation of the bank and are arranged todetent the timer under certain conditions of operation.

A manually operated cutout switch is provided in line 46 in combinationwith a down push button dispatching control that may be used to givedown dispatching signals manually in advance of or in addition to thetimer initiated down dispatch signals. Thus if a starter should pressthe down dispatch button in line 46 he would immediately reset the downdispatch relay KD thus giving a dispatch signal. Since this may occurprior to the closing of the timer contacts A in line 45 the cars may bemanually dispatched ahead of the regular timing interval. A cut outswitch CO is provided to prevent unauthorized manual dispatching.

The up dispatching circuits include more relays since they provideadditional functions. For example, a starter at the lobby floor may beprovided with a release control which holds the cars at the lobby floorwithout a through up dispatch relay contacts KU in the same line. Thusthis circuit for the starter release dispatching relay SR cannot becompleted until the up dispatch latch relay KU in line 54 has been resetby current flow through the bottom dispatch timing motor contacts TMB-Ain line 54. Therefore, the ordinary up dispatch time signal interval isfirst given by closing the contacts TMB-A in line 54 to reset the updispatch latch relay KU. This in turn prepares a circuit for the starterrelease relay SR. Since it is undesirable to require the starter to holdthe starter release push button SRP closed until the car leaves, asealing contact SR in line 58 is provided to bypass the push button assoon as the starter release relay SR is energized. Should it bedesirable to eliminate or bypass the starter release push button SRP acutout switch in line 57 is closed to maintain the circuit for thestarter release relay continuously prepared so that this relay isenergized as soon as the latch relay KU is reset.

Manual dispatching is also provided by means of the cutout switch inline 47 and an up manual dispatch button in the same line. When thisbutton is pushed, provided that the cutout switch is in the positionshown, current flows from the =line L3 through the cutout switch in line47, the push button in the same line, then through the coil of themanual dispatch relay MDT in line 48 and through the up dispatch latchrelay contacts KU in the same line. These dispatcher relay contacts KUare closed as soon as the relay is tripped following the departure of acar from the lower floor. The manual dispatch relay MDT thereupon closesits contacts in line 48 to seal itself in and closes its contacts inline 50 to permit current to flow through the normally closed bottomdispatch timer relay contacts TMB-C, the now closed manual dispatchcontacts MTD in line 50 then through an interval reset relay RF in line49. This relay immediately closes its contacts in line 51 to establish aholding circuit. The manual dispatch relay MDT is of the quick pickupslow release type so that it maintains its normally open contacts closedfor a brief time interval after its coil is de-energized.

As soon as the interval reset relay RF in line 49 is energized it closesits contacts RF in lines 58 and 60 to energize the timer relay resetmotor 18. It will be recalled from Figure II that the timer reset motor18 is arranged to drive the cam shaft of the dispatch timer at a highrate of speed. Therefore the cam is rapidly driven around to first closeits timing contacts TMB-A at line 54 thereby energizing the reset coilof the up dispatch relay by means of current flowing from the line L3,through the timer contacts A in line 54, the manual dispatch relaycontacts MDT in line 55 and the reset coil KU of the up dispatch relay.As the up dispatch relay KU is reset it opens its contacts in line 46thereby de-energizing the manual dispatch relay MDT. This relay being ofthe slow release type, does not immediately release but maintains itscontacts closed for a brief time interval thereafter. The interval resetrelay RF, however, is still energized through its own contacts RF inline 51. Therefore the reset motor 18 continues to run at full speeduntil the dispatching mechanism comes around to open the contacts TMB-Cin line 50 thereby de-energizing the interval reset relay RF andstopping the motor 18. Thus within a very short time from the pressingof the up manual dispatch button in line 47 the bottom terminaldispatching machine timer is advanced, first to give an up dispatchsignal by way of the starter relay release relay SR energized when theup dispatch relay KU is reset, and then to continue the timer rapidmotion until the contacts TMB-C are open thereby setting the timer togive a full time interval before the next regular dispatching signal.

It is, of course, assumed under this condition of manual dispatchingthat the starter release push button SRP in line 56 is bypassed by thecut-out switch so that the dis- 16 patch signal is given immediatelyupon the reset of the up dispatch relay KU.

The bottom terminal dispatching timing motor TMB may be detented, thatis stopped, under certain conditions. Thus if the contacts DU shown inline 37 are open by energization of the up detent relay DU in line 52the timing motor is stopped. The up detent relay DU is energized whenthe dispatch timer closes its TMB-B contacts shortly before it wouldgive a regular signal in the event that: (a) there are no callsregistered requiring movement of any car, i. e. the contacts SSC in line53 are closed; (b) the program is set for immediate up dispatching toserve heavy down trafiic in which case RU contacts in line 51 areclosed, or (0) there may be no cars at the lower terminal available fordispatching which condition is indicated by closure of the BDT contactsin line 52. Under any of these conditions the up detent relay DU isenergized as soon as the timer reaches a position approximatelyone-tenth of a normal time interval before the next regular dispatchsignal. The timer stops at this position and waits until dispatchingsignals are again required.

An additional feature is the resetting of the up dispatching timershould a car leave the bottom terminal before the receipt of adispatching signal. Should this occur Within a certain minimum timeinterval from the time that car was available for loading at the lowerterminal then current may flow from the line L3 at line 49 throughbottom terminal minimum time relay con tacts BDTZ, then through the carcounting reset relay contacts NCBR that close momentarily as a carleaves the terminal, then through contacts KUT of an auxiliarydispatching timing relay to the coil of the interval reset relay RF. Inthis circuit the contacts KUT are closed as long as the coil of therelay KUT in line 12 is deenergized. This occurs as long as there is nodispatching signal registered. Likewise this condition holds for a fewmoments after a dispatching signal is registered. The energization ofreset relay RF advances the timer cam rapidly until the TMB-C contactsopen, which occurs just after the normal dispatch signal position. Thedispatch relay KU is not reset as the cam turns past the normal dispatchposition because contacts RF in line 54 are open during this resetoperation. This has the effect of resetting the bottom terminaldispatching timer to give a full time interval for the next car toleave. Without this feature if the car leaves ahead of the receipt ofthe regular dispatch interval the next car will receive a dispatchsignal as soon as it arrives and thus the timing is too short. If thenext car ignores the first dispatch signal to Wait for a second thetimer detents and there is no second signal. The resetting of the timeras the car leaves, however, avoids these difiiculties and provides aregular full timing interval for the next car in the event that the carleaves without the receipt of a signal. It should be noted that thisreset occurs only in the event there are no other cars available forloading at the main terminal. If other cars are there then the dispatchselector contacts BDT2 are open and this resetting circuit cannot becompleted.

The improved dispatching mechanism including independent timing motorsat the upper and lower terminals provides for automatically balancingthe system regardless of the number of cars in operation and regardlessof their distribution. Thus the unexpected changes in load which maycause unbalance or unexpected delay of a car in responding to adispatching signal is corrected almost as soon as it occurs by theaccumulation of too many cars at one terminal. Such an event immediatelychanges the dispatching intervals in opposite directions at the twoterminals so as to correct the unbalance immediately. This isautomatically accomplished without changing the average dispatchinterval and thus with a minimum of disturbance of the system.

Various modifications in circuits and details of component parts may bemade without losing the advantages to the self-adjusting dispatchingsystem just described.

Having described the invention, I claim:

1. In a dispatching system for a group of elevators, in combination, amotor driven dispatch signal timer for each terminal, relays forsignaling the presence of a car at a terminal floor, contacts operatedby said relays, a number of cars signal relay for each terminal floor,circuit means including said contacts for operating thev correspondingsignal relay when a predetermined number of said contacts associatedwith the corresponding terminal are closed, and speed control means foreach of the motor driven signal timers, said signal relays beingoperatively connected each to both speed control means and adapted tosimultaneously vary the motor speeds to reduce the dispatch interval forthe terminal corresponding to the actuated signal relay and to increasethe interval for the opposite terminal.

2 In a dispatching system for a group of elevators, in

combination, a motor driven dispatch signal timer for each terminal,relays for signaling the presence of a car at a terminal floor, contactsoperated by said relays, a number of cars signal relay for each terminalfloor, means including said contacts for energizing the signal relayswith currents proportional to the number of elevator cars standing atthe corresponding terminals, and speed control means for each of saidtimers controlled by said signal relays and adapted to decrease thedispatch interval at the terminal having more than a predeterminednumber of cars standing thereat and simultaneously increase the intervalat the opposite terminal.

3. In a dispatching system for a group of elevators, in combination, amotor driven dispatch signal timer for each terminal, means forsignaling the presence of a car at a terminal floor, a dispatchercontrol relay for each terminal, means operatively connected to thesignaling means for operating the dispatcher control relay when apredetermined number of cars accumulate at the terminal, interconnectedspeed control means for said motor driven signal timers, said speedcontrol means being operatively connected with the control relays suchthat operation of a control relay decreases the timing interval of theassociated timer and increases the time of the opposite terminal timer.

4. In a dispatching system for a group of elevators, in combination,means for generating dispatching signals one for each terminal, speedcontrol means for simultaneously increasing the dispatch interval at oneterminal while decreasing the interval at the opposite terminal,signaling means for each elevator for signaling the presence of theelevator car at a terminal landing, said speed control means beingjointly controlled by said signaling means to respond to thesimultaneous reception of a predetermined number of signals.

5. In a dispatching system for a group of elevators,

a motor for driving each machine, speed control means for each motoradapted to drive the motor at any of three speeds, signal means for eachelevator for signaling its presence at a terminal floor, and a relay foreach terminal floor, each relay being controlled jointly by the signalmeans to respond to a predetermined number of signals, each relay beingconnected to the speed control means to reduce the speed of one motor toits slow speed while simultaneously increasing the speed of the othermotor to its high speed.

6. In a dispatching system for a group of elevators, in combination, adispatching machine for each terminal, a direct current motor fordriving each dispatching machine, an alternating current power source, aplurality of transformers and rectifiers adapted to be connected to thepower source for supplying direct current to each of the direct currentmotors, said rectifiers having their output circuits connected in serieswith the motor whereby the motor speed varies with the number oftransformers connected, means for each elevator car for signaling itspresence at a terminal floor, and a relay for each terminal floor havingcontacts connected in circuit with said transformers and arranged whenenergized to disconnect one of the transformers feeding the motor at theopposite terminal and connect one of the transformers for the motor atthe adjacent terminal, said relays being jointly energized by saidsignaling means and arranged to respond when a predetermined number ofsignals are simultaneously received.

7. In a dispatching system for a group of elevators, in combination, adispatching machine for each terminal, a direct current drive motor foreach dispatching machine, an alternating current power source, atransformer for each motor having its primary connected to the powersource, a rectifier connected between the secondary of the transformerand the armature of the motor, at least one other transformer andrectifier for each motor with the rectifier connected in series with thefirst rectifier, signal means for each elevator for indicating itspresence at a terminal floor, a relay for each terminal floor controlledjointly by the several signaling means and responsive to a predeterminednumber of signals, and contacts on said relays arranged to switch saidother transformers into and out of circuit to vary the speeds of themotors.

8. A dispatching system according to claim 7 in which the voltage of thealternating current power source is adjustable.

Eames Jan. 6, 1953 Borden et al. Sept. 22, 1953

